(1) FIELD OF THE INVENTION
This invention relates to thyratrons, and concerns in particular devices for the extremely rapid switching of large electric currents from one circuit to another.
(2) DESCRIPTION OF THE PRIOR ART
In certain areas of the electronics field there are many occasions--for example, in the operation of radar and allied systems--when it is desirable, for one reason or another, not only to switch between circuits or circuit elements carrying relatively large currents (possibly as large as several thousands of amps) but also to effect the switch-over operation extremely rapidly--perhaps in as little time as a few microseconds. Conventionally such currents can easily be switched on in such a short time using as the switching device a thyratron (a type of thermionic valve containing a low pressure gas which under the right conditions can be ionised within a few nanoseconds to give a plasma of very high current-carrying capacity), but unfortunately thyratrons cannot easily be switched off so quickly, and to date no entirely satisfactory rapid "switch-off" device has yet been found. As a result, it has proven difficult to obtain an acceptably rapid "switch-over" device.
Most of the efforts to find a rapid switch-off device have involved thyratrons of various types, and considerable promise has been shown by thyratrons wherein the plasma carrying the current between the thyratron's anode and cathode is caused to pass through a magnetic field so orientated as to divert the plasma particles out of the main current pathway (whereupon the through-valve current drops, the plasma is quenched, and the current is interrupted). Nevertheless, none of the thyratron designs built so far have proved entirely satisfactory as switch-over devices.
The invention seeks to solve this difficulty by using the principle of plasma particle diversion together with a new thyratron design.